The aperture location is part of the optical design of the lens and its position is dictated by the position and nature of the individual lens elements. You can't just put it anywhere.
There are lenses with the aperture as part of the shutter, but in those lenses (leaf shutter lenses), the shutter is located somewhere in the middle of the lens (i.e. between the lens elements).
You can use a front aperture in some circumstances, such as with a simple, long telephto lens. A classic example is a telescope, where you can place an aperture over the front of the lens in order control the effective aperture (f-stop).
I was thinking more along the lines of whether there is a virtual image where you put the aperture or is it at the exact opposite of a virtual image - whatever that would be called. I would think it would go about the same place as the IS element. The place in the lens where the light is necked down, but completely defocused - if that is the right term.